Outlet guiding arrangement



May 13 1952 A. BUcHl OUTLET GUIDING ARRANGEMENT Filed Oct. 17, 1951 4Sheets-Sheet l 10' IN1/wma May 13, 1952 A. Buca-n 2,596,646

OUTLET GUIDING ARRANGEMENT 4 Sheets-Sheet 2 Filed 0012. 17, 1951 may 55,w52 A. BUCHI OUTLET GUIDING ARRANGEMENT 4 Sheets-Sheet 3 Filed OCT.. 17,1951 May E3, i952 A. BUCH! OUTLET GUIDING ARRANGEMENT 4 Sheets-Sheet 4Filed 001'.. 17, 1951 uil fi? i@ Patented May 13, 1952 OUTLET GUIDINGARRANGEMENT Alfred Buchi, Winterthur, Switzerland Application October17, 1951, Serial No. 251,741 In Switzerland January 19, 1946 (Cl. S-111) 11 Claims. 1

This invention relates to an improved outletguiding arrangement forcentrifugal blowers and pumps. The present application is acontinuation-in-part of my application Ser. 723,080, filed January 20,1947, which has been abandoned.

The efficiency of a centrifugal pump or blower depends not only uponsuch factors as the rotor speed, bearing friction, rotor disc friction,shock Y losses at the rotor intake and outlet, but also upon the ductarrangement whereby the fluid leaving the periphery of the rotor bladingunder high velocity and in a direction having a substantial tangentialcomponent is captured, its y embodiment a series of guide duct diiuserswhich are directed Substantially tangentially from the rotor blading andare at least partially axially deflected towards a scroll space, itselfoffset .axially of the blower rotor. In such an arrangement, I definethe scroll space by a portion of the blower housing which includes alateral wall provided with a series of openings.

The diliusers discharge their pressure fluid via these openings into thescroll space so partially defined by such lateral Wall, in asubstantially circumferential direction. It is my preference that thediffusers themselves should not project through this lateral wall sothat the inner wall defining the scroll space presents a smooth contourto the pressure fluid passing therethrough.

It is also an object of my invention to provide a duct arrangementwherein at corresponding points in the arrangement equal speeds andpressures of the fluid are maintained, thereby to reduce impact lossesin the fluid as it passes from the diiiusers into the scroll space orspaces.

It is also an object of my invention to provide an arrangement which indierent embodiments may utilizeV duct diffusers of several different' 1scroll space,thereby,to reduce 130W losses.

It is also an object to effect the circumferential deection of the fluidstreams into the scroll space under the Widest radius of curvature.

These and other objects are attained in the apparatus hereafterdescribed and illustrated in the accompanying drawings in which areshown Fig. 1, an axial section of a single stage blower taken on lineI--I of Fig. 2,

Fig. 2, an intake-end or plan View of the latter, partly in steppedsection on line II-II of Fig. 1 through rotor and outlet guidingarrangement.

Fig. 3, a partial axial section through the said blower, illustrating amodified design of the outlet transition portion from rotor-gap toguideduct,

Fig. 4, a section of the said blower, transverse of the rotor aXis andon the double-curved center line of one of the six guide-ducts, on curveIII-III of Fig. 8,

Fig. 5, a partial section similar to Fig. 4, illustrating a modifiedtransition at the entrance to the guide-duct diffuser proper,

Fig. 6, a cross-section on line VI-VI of Fig. 5,

Fig. 7, a series of consecutive cross-sections through theguiding-arrangement of Fig. 4 on the lines IV-lV to IX-IX thereof,

Fig. 8, a section, more in a tangential direction, on the center line ofa guide-duct diffuser, inclusive of the lateral collecting scroll case,

Fig. 9, a section, transverse of the rotor axis and on the single-curvedcenter line of a modified guide-duct diffuser indicated by dash lines inFig. 8,

Fig. 10, a tangential developed Section through the rst guide-ductdiffuser, the scroll case, and the final delivery bend,

Fig. 11, a section, similar to Fig. 10, of a modifiedguiding-arrangement which affords a scroll case having a smooth outsidewall.

Figs. 12 and 13, an intake end-view and elevation respectively of aguide arrangement comprising three outlet scroll cases and final bends;Fig. 13 showing also an air filter.

Fig. 14, a longitudinal section through a blower with six stages,including a cooler,

Fig. 15, a cross-section taken on the line XV-XV of the blower shown inthe apparatus, and

Fig. 16, a section similar to Fig. 15 but showing a modified embodimentof the return duct arrangement.

Vand witha minimum of turbulence.

ing 3a encloses the rotor I. A portion 3 of this housing 3a forms afunnel which provides the entrance area for the fluid to be compressed.The discharge of the pressure uid from the blading II is eiected intothe clearance gap 4 which surrounds the rotor I.

In this preferred embodiment of my present invention I have shown eightsickle-shaped discharge openings 5 which originate in the portion la ofthe housing 3a, which portion partially defines the gap Il. Theseopenings 5 serve toconduct the pressure iiuid into rectilinear diffusers6 which are directed substantially'tangentially with respect to therotor I and transversely of the blower axis. Following each of theserectilinear diffusers 6, I have shown further guide duct portions 1, thewalls of which will be seen in Fig. 2 to diverge from each other for atleast part of their extent.- These portions '1, moreover, arecurvedtangentially as wellas axially of the rotor I so as rto deliverthe pressure fluid directlyinto a scroll space fwhi'chis disposedlaterally offset of `the rotor I. The scroll space 8, dened by the .wallB ad, itself a Vportion of the blower housing 3a, is shown in Figs. land 2, as an annular chamber originating at guide duct portion I anddischarging into'pres'sure branch 9. The latter may be constructedeither as a'pipe of uniform crosssection (as shown byfthe dash-and-.dotlines of lf'ig. 2) orasfa further diffuser (as shown by the fun linesof'rig. ,2).

An important feature of my invention is the manner in which I disposethese curved portions A'I -to discharge the pressure uid into the scrollspace 8.A Thel curved diffuser portions 'I are disposed to approach thenearest side 8b of the Wall `8a vat siich' angle that the pressure fluidis admitted into the scroll space 8 in a direction which issubstantially.circumferential of the blower. The 'sidejSb of the. wall8a is, in effect, cut to accommodate the intersection therethrough ofthe curved portions 1, andthe latter are then cut oi alongthe,'linesofintersection which, in this embodimentf are shown to lie inthe plane I0, normal to `tlfieirotor axis. As a result of these cut-offsof "the'curved portions 'I it will readily be seen that the side 8 1) ofthe wall 8a is provided withfa 'seresjof substantially ellipticalorifices at eachintersection, but otherwise the inner area of the entireWailea, including the side ab, is without protrusion. This scroll wallsmoothness Vaiordsexcellent'iiow characteristics within the scrollspace.Each iiuid stream (subsequent to the r'st, flowing-through th-e curvedportion 'i' 'which constitutes the head of the'scroll) will thus befound to join the preceding stream or combination of'streams in the mostnatural manner This particular feature of my invention may be employedin any guide' vduct arrangement with noticeable improvement (inperformance e'ciency, regardless of whether; the' other features of myinvention, particularly those pertaining to my preferreddiffuser'arrangemena'are also adopted.

To further improve the flow characteristics of theiarrangement, Irecommend also that the outlet opening of at least one curved portion 'lbe so disposed as to discharge the pressure fluid directly into'an'exitconnection branch 9 in the direction of the latter. This is illustratedby 'I" in Fig. 2, and is also shown in Figs. l and 1l.

The clearancegap 4, as well as the discharge openings are shown Vin rnypreferred embodi- 'nientv (Fig.` 1) as being defined lby parallel walls4a which Walls are at right angles to the blower axis. This constructionresults in the approximately rectangular cross-sections IV-IV and V-V ofthese passages shown in Fig. '7. These walls may, however, beadvantageously uniformlyv or non-uniformly enlarged to diverge outwardlyas shown in Fig. 3 to give trapezoidal cross-sections. y

The details of construction of theugap 4, an opening 5 and the ensuingrectilinear diffusers 8 and curved diffuser portion in my preferredembodiment are shown in Figs. 4 and 7. The curved portion I will be seento be twisted radially as well as axially before passing the pressureiiuid into the scroll'space 8 which, as previously stated, is laterallyoffset with respect to the rotor.

The transition of the pressure fluid from the sickle-shaped opening 5 tothe rectilinear diffuser portion 6 is illustrated in a larger scale inFigs. 5 and 6. From 'these latter figures itwill be'seen that Ipreferablyv interpose a parallelwalled circular duct portion I21f in theareafof transition ofthe pressure fluid between the'channel'of opening 5and the rectilinear diffusent, i. e.,'between lines I2* and I3 of Fig.5. This circular duct portion I2a serves to bring the pressure fluidintoavl straight vpath with uniform velocities and pressures at the'entrance I3 to diiuser portion 6, after the fluid has initiallyflowedalong the curved walls"y Irland I5 atfdifferent velocities becauseof torsional effect and the disturbance "in its movementfwithin therange of the' entering edge IB. Attaining this uniformity at the"entrance I3 to diffuser portion 6, enables the latter more effectivelyrtoconvert velocity into pressure. The transition inthe crosssections I2and I3, however, should be well rounded, i. e., sharp edges should beavoided, This preferred cross'sectional shape is shown in VI-VI of Fig.7. n

While I have shown in'my preferred embodiment the walls I1 of thestraight diffuser portion 6 and the'curved diffuser portion 'I asdivergng uniformly over the entire length of these portions, i'. e., ata constantangl'eofdiversion, in `Asome instances it might be desirableto'V provide 'for `the diversion of the'walls in these portions atdierent angles. For examplea'small angle'might be best suited atth'eentrance I3 to the diffuser portion 6 where the fluidfism'oving-at highvelocity; the angle of divergence might then be gradually increasedporportional 'to the Vdistance from diffuser entrance, in this'way tolprovide an'optirn'um angle of divergence for the fluid 'velocityYoccurring in each segment of the diffuser portions.

It will further be seen from sections'VIL-N11, VIII-VIII Figy, :that IVhave preferably' constructed thesev guide 'duct diffuser portions withcircular cross-'sections in order 'to keep friction and conversionvlosses 'therein to a minimum. While the' cross-section` IX-'IX at thedischarge outlet appears to be semi-circulan-'it'willbeborne in mindthat at such' section oneihalf of the pressure fluid has' already been'transferred rinto* the scroll space 8. It Yisalso"izle'sirableto 'makethe radius of curvature of the guide-duct portion i relatively large to'avoid large "deflection losses as well as to minimize 'friction andconversion losses. 'Moreoven 'as shown in Figs: l'and 4, the initialdesirable 'large radius of curvatiireat the entrance to thecurveddilfu'ser portionLmay'be gradually decreased'towards the diffuserexit into the scroll space 8.

I also prefer, in the construction of myrdiffus'ers, that thenarrowestjcross-sectional area'VI-VI at thel entrancey intothestraightdiffuser. 6; be somewhat smaller than the cross-sectional areaimmediately adjacent the point I6 where the fluid enters the ductseries. In this manner there may be avoided any substantial pressurelosses which would tend to occur because of the necessarily sharper andmore irregular deflection ofthe lwalls I4 and' I5 (especially thelatter) of the intake channels 5 from the at least partly rectangular,trapezoidal or other cross-sectional shapes into the preferably circularcross-sectionally-shaped entrance of the straight diffuser 6. By thusmaking the Ycross-section at VI-VI narrower than that at V-j-V, Vthevelocity of the pressure fluid is accelerated between these sections sothat minimum losses occur even in the case of relatively small andnon-uniform radii of curvature there exi-stent. Greater conversion ofvelocity into pressure is then possible in the adjoining guideductportions 6 and 1. v

In the view shown in Fig. 8, the laterally curved axis of the portion 1and the straight axis of the portion G will both be seen to lie in oneand the same plane I8 indicated by the dash-and-dot lines. By thisdisposition of these axes, I eifect the desired laterally deflected flowof the pressure fluid toward the scroll space 8 in accordance with myinvention. In this embodiment it is possible to arrange thecross-sections of side-walls I1 of the portions 6 and 1 at right anglesto plane I8; these side walls maybe rectilinear in the same directionand provided with the same angle of divergence as is shown in Fig. 9.The most pronounced curvature of the guide-duct portion 1, in thisembodiment, then occurs in plane I8; at right angles thereto there wouldoccur no curvature in said portion with the result that deflectionlosses in portion 1 would be less than if the axes of guide-ductportions B and 1 were not so situated in one and the same plane.

Following the course of a particle of the pressure fluid, it will beseen that, upon leaving the rotor blading I I, the particle is projectedinto the clearance gap 4, thence passing into one of the intake openingsor channels 5. From here it moves onward into the straight diffuserportion 6, the axis of which approximately coincides with that of theintake channel 5. Next the particle ows into and through the curvedguide-duct diffuser portion 1 into the scroll space 8, laterally offsetwith respect to the rotor; and finally into the outlet tube 9.

The pressure fluid particles entering the other guide ducts similarlyflow through the latter and enter the scroll space 8 via the respectivecurved portion 1 of each duct. I also prefer to make a gradualenlargement of the cross-section of the scrollv space 8 as eachadditional fluid stream enters this space, so as to enable the inflowingpressure fluid to be conducted onward through the scroll case withminimum losses, i. e., at approximately the same velocities. Thisincrease in cross-section of the scroll space is illustrated in theembodiments of Figs. 10 and 11 in which five sets of guide-ducts 4-1 areshown.

In the embodiment of Figs. 12, 13 I have shown three outlet tubes 9, 9',9 instead of the single tube of the Figs. 1, 2, l0 and 11 embodiments.Into each tube is discharged' the fluid of two guide-ducts 4-1, althoughthree or more guide ducts 4-1 could be combined to deliver pressurefluid into one of a plurality of outlet tubes 9. Embodiments whichinclude a plurality of scroll cases 8 and outlet tubes 9 are usefulwherever the pressure has to be delivered to several places of use, suchas coolers, etc.

It is'also a feature of my invention to consmooth walls of such contourthat when the two' struct such a guide-duct arrangement as hasheretofore been" described as a two-part casing divided in a planenormal to the rotor axis and passing approximately through the center ofthe rotor. Each half of this casing may be 'oppositely die cast orotherwise formed to provide thus-cast or formed halves are broughttogether in the same plane, a rotor housing and guideduct-scrollarrangement in accordance with my invention will be found to result.Suitable means such as bolts 20 may be employed to secure these twocasing parts together.

In the apparatus of Fig. 14, reference characters I-I""f designate sixrotors driven by the same shaft 2. From a study of this figure it willbe observed that the pressure fluid is discharged from each rotor into aclearance gap 4, thence passing to intakes 5, and to straight diuserportions 6. In the case of each of the four rotors I, I', I and I", thepressure fluid is further delivered into the guide duct portions 1 whichare preferably curved and diverging both in a tangential as well asaxial direction, in accordance with the principles of my inventionheretofore discussed. From these portions 1, the pressure fluid thenilows into the scroll cases 8, 8', 8" and 8"" arranged respectivelybetween the first and second, the second and thirdl the fourth andfifth, and the fifth and sixth stages. The walls I9-I9" (shown as dottedlines) of the guide duct portions 1 indicate the deflection of thelatter toward the scroll cases 8, 8', 8 and 8". The pressure fluid isdischarged from the portions 1 immediately to the outer circumference ofthe scroll spaces 8 in a tangential direction which is initiallymaintained in the scroll cases. It should be noted that after the fluidleaves the third rotor I", it passes through a cooler 20, thence backinto the eye of the fourth blower I via duct ZI. It should also be notedthat since the entire guiding arrangement leading to the cooler iscentered about a plane at right angles to the blower axis andr itselfcentered with respect to the rotor I", it is not necessary to constructthis guide arrangement 4--1 in accordance with my present invention, butinstead it may be .laid out in accordance with prior art.

Instead of one cooler 20, I may provide a plurality of coolers.

The guiding arrangement for the last rotor may be constructed, eitheraccording to my present invention with axial deflection, or without suchdeflection similar to the arrangement for rotor I.

Fig. 15 shows how the pressure medium flows from the eight guide-ductportions 1 first tangentially, and thence into the ducts 23 formed bythe outstretching blade portions 22. The ducts 23 conduct the mediumradially inward toward the blower shaft 2 into the eye of the next stageI. In this preferred embodiment, I suggest that the blading 22 should bedimensioned to provide such cross-sectional areas for the ducts 23 thatvelocity losses are kept at a minimum.

In the Fig. 16 embodiment, I have shown the vanes so dimensioned anddisposed as to make the guide-ducts 23 of uniform cross-section. Theseguide-ducts convey the medium separately from the curved diffuserportions 1 into the annular entrance chamber 24 to the next rotor I.This arrangement may also be applied to the stages I', l" and I"".

If the principles of my invention described aboveY are applied in theAmanner recommended,

a guide-duct arrangement of materially increased lAll these I intend tocomprehend within the scope of my invention.

IV claim:

l. In-a centrifugal blowerorpump having a bladed rotor and ahousingrenclosing said rotor, a delivery guiding arrangement including aseries of guide-duct -diffusers extending `through-'said housing andradiating from-the rotor periphery, said `diffusers1`-oeing directed atleast partially axially of the =blowcr,\ said, rhousing also havingaportion forminga scroll space, said `diffusers being disposed outsideof said housing-portion form-ing said scroll `space Yand said scrollspace being offset axially on the samev side of the rotor toward which-said diffu-sers laredirected, said housing portion forming said scrollspace including a wall defining the side of the scroll space adjacentsaid diffusers, said wall being provided with a series of openingscorresponding in number Lwith the number of said `diff-users andregistering with their disclnirgey orifices, saiddiffusers extending,however, only tothe edges of said wall definingv said openingsand saiddiffusers being disposed to approach said wall at such'angle that the:pressure Afluid from the said diffusers is advmitted into thescrollfspace in substantially cir- -stantially cylindrical wallsurroundingconcentricallyfthe rotonsaid wall-having a series of orificesthrough 'its circumference disposed. radially beyond the rotor blading,aplurality of intake canals beginning 'at said orifices `and extendingsubstantially tangentially from saidcylindrical wall to receive theii-uid from the rotor blading,

a plurality of guide-duct diffusers, one communicating witheachof-saidorifices, each continuing the nuid passageof onel of saidcanals yand each said diffuser having two distinct consecutive portionsconsisting-*oa `divergent fronti portion with a straight axis lying.-substantially in a radial plane -relative to the blower-,axis nand adivergent rear portion with an -axis ldeflected axially of the blower,-bothportionsbeing adapted to convert the 'velocity' -head -of v thev"fluid-into pressure head, a casing portion forming -a Yscroll space,said ydiifusers Abeing disposedv outside of said casing portion formingsaid scroll space and said scroll space 'being offset "axially from, butadjacent tosaid guide-duct diffuser rear-portions, said casing-portion-beingz provided with a series of'openings on the sidethereofadjacent tosaid diffuser rear portions,said openingscorresponding in number with the number-of guideduct diifu'sers` andiregisteringfwiththe ldischarge orifices of said guide-'duct diffuserrear portions, said rear portions extending, however, only to the edgesof said casing .portion denningasaid several openings, and saidrearsportions being disposed to approach said casing portion atfsucn anangle that the pressure iiuidffromthe said diffusers is admitted intoYthescroll space in Asubstantially circumferential directioni 3. In acentrifugal blower or-pump having a bladed rotor, a delivery vguidingarrangement `Ycomprising;4 a` collecting `chamberfformed; by asubstantially cylindrical wall surrounding con- Y Yg centricallytherotor, r`said wallhaving a1series of orices through its circumferencedisposed radiallylbeyond the rotor blading, a plurality vcf intakecanals beginning at said orifices and extending substantiallytangentially from said portion with a straight axis and a-divergent rearportion with a deflected aXisbOthsaidaxes being disposed in one and thesame plane,rsaid plane extending obliquely to theblower axis, and

both saidv diffuser portions being 'adapted ito convert-the velocityhead of .the fluid intor pressure head, a casing portion forminga-scroll space,said diffusers beingdispos'edoutside of said casingportion forming said scroll.-space and said scroll space being offsetaxially frombut adjacent to said guide-duct diifuserrear portions, saidcasing portion being provided with a series of inlet openings onvtheside thereof adjacent to said diffuser rear portions, said openingscorresponding in number with the number Aof guideduct diffusers andregistering withV the discharge orifices of said guide-duct diifuserrearportions, said rear portions extending, however, only to the edges ofsaid casing portions defining said several inlet openings, and said rearportions being disposed to approach said casing 'portion at such anglethat the pressure fluid is admitted into the scroll space insubstantially circumferential direction.

4. In a centrifugal blower or pump having a bladed rotor, a deliveryguiding arrangement comprising a collecting chamber formed by asubstantially cylindrical wall surrounding con- -centrically the rot/or,said Wall having a series of orifices through its circumference disposedradially beyond the rotor blading, a plurality of guide-duct dilfusers,one .communicating with each of said orifices,` each said diffuserhaving two distinct consecutive portions consisting of a divergent frontportion with astraight axis lying substantially in a radial planerelativerto Vthe `blower axis and-a divergent rear portion Withan axisdeiiected axially of the blower, both portions being adapted to convertthe velocity head ofthe fluid into pressure head, a casing portionforming a scroll space, said diifusers being disposed outof guide-ductdiusers and registering. with the discharge orifices of said guide-ductdiffuser rear portions, said rear portions extending, however, only tothe edges of saidcasing portion dening said several openings, and saidrearfportions being disposed to approach saidcasing portion at such'anangle that the pressurel fluidf from the said diifusers is admitted intothe-scroll space 'in substantially circumferential direction.

lav front-portion with a straightaxispaseries of intake canals areprovided to receive the uid tangentially from the rotor periphery, eachof said canals communicates with and precedes one of the guide-ductdiffusers, and a guide portion is interposed between the entrance ofeach said canal and the front portion of the diiuser with which itcommunicates, said guide portion being substantially coaxial with thesaid guide portion.

7 A delivery guiding arrangement as set forth in claim 1 wherein aseries of intake canals are provided to receive the fluid tangentiallyfrom the rotor periphery, each of said canals communicates with andprecedes one of the guideduct diiusers, and the cross-section of thefront portion of each of said diifusers is smaller than thecross-section of the entrance of the intake canal communicating withsaid diffuser.

8. The delivery guiding arrangement as defined in claim 1 wherein eachof the guide-duct diiusers includes a rear portion having a curved axisand at least one of said rear portions opens directly into an exitconnection branch in the direction of the latter.

9. The delivery guiding arrangement as dened in claim 1 wherein each ofthe guide-duct diffusers includes a rear portion having a curved axisand at least one of said rear portions opens into the head end of atleast one scroll casing.

10. A delivery guiding arrangement as described in claim 1 wherein thesaid guide-duct diiusers are constituted of a surface of a first casingpart, said surface being appropriately a 10 formed to dene a portion ofsaid diffusers, and of an oppositely formed surface of a second separatecasing part, said two surfaces being brought together in a plane normalto the axis of the pump or blower to register the correspondingformations of both said surfaces.

11. The delivery guiding arrangement as described in claim 10 whereinthe side of one of said casing portions opposite the said formed surfaceforms a scroll space provided with a series of openings with which theguide-duct diffuser rear portions communicate.

ALFRED BUCHI.

REFERENCES CITED The following references are of record in the le ofthis patent:

UNITED STATES PATENTS Number Name Date 1,392,090 Tamini Sept. 27, 19212,289,231 Auger et al. July '7, 1942 2,311,024 Buchi Feb. 16, 19432,405,048 Nickerson July 30, 1946 FOREIGN PATENTS Number Country Date146,064 Switzerland June 16, 1931 170,815 Great Britain Oct. 14, 1921400,465 Germany Aug. 19, 1924

